福州大学郑仕标团队近日研究了量子力学系统中Weyl异常环的实现与拓扑表征。2025年6月4日出版的《科学进展》杂志发表了这项成果。

非厄米性可以导致许多在厄米系统中不存在的有趣现象的出现，这些现象是由特殊的拓扑缺陷实现的，其中Weyl异常环（WER）特别引人注意。量子阱的拓扑结构可以用量子化的Berry相位和非零的Chern数来表征，它们都编码在非厄米哈密顿算子的特征向量中。到目前为止，研究组已经用经典的波系实现了量子阱，这些波系的特征向量可以用经典物理很好地描述。

研究组报告了量子力学的第一个实现，并研究了相关的拓扑跃迁。实验系统由一个超导量子比特和一个耗散谐振器组成，它们相互耦合。系统的高灵活性使他们能够在参数空间的不同流形上表征其特征向量，每个特征向量对应于一个量子力学纠缠态。研究团队从这些特征向量中提取量化的Berry相位和Chern数，并演示了通过缩小流形的尺寸触发的拓扑转换。

附：英文原文

Title: Implementation and topological characterization of Weyl exceptional rings in quantum-mechanical systems

Author: anonymous

Issue&Volume: 2025/06/04

Abstract: Non-Hermiticity can lead to the emergence of many intriguing phenomena that are absent in Hermitian systems, enabled by exceptional topological defects, among which Weyl exceptional rings (WER) are particularly interesting. The topology of a WER can be characterized by the quantized Berry phase and a nonzero Chern number, both encoded in the eigenvectors of the non-Hermitian Hamiltonian. So far, WERs have been realized with classical wave systems, whose eigenvectors can be well described by classical physics. We here report the first quantum-mechanical implementation of WERs and investigate the related topology transitions. The experiment system consists of a superconducting qubit and a dissipative resonator, coupled to each other. The high flexibility of the system enables us to characterize its eigenvectors on different manifolds of parameter space, each of which corresponds to a quantum-mechanical entangled state. We extract both the quantized Berry phase and Chern number from these eigenvectors, and demonstrate the topological transition triggered by shrinking the size of the manifold.

DOI: 10.1016/j.scib.2025.05.041

Source: https://www.sciencedirect.com/science/article/abs/pii/S209592732500581X